Distributing valve for pneumatic hammering tools



F. P. FORSS I Nov 1 ,1943.

DISTRIBUTING. VALVE FOR PNEUMATIC HAMMERING TOOL Filed Dec. 30, 1940 3 Sheets-Sheet l 5 aww w M 1 ATTORNEY New. 16, 1943.

3 Sheets-Sheet 2 Filed Dec. 30, 1940 INVENTOR. fiw/w/or fb/ess ATTORNEY.

99 7 d #0. MM 4 A Q a 6 J w 8 Z 3 J .2 z fl V a w I z 6 w I 2 a.

Nov. 16, 1943. F, P, FORSS 2,334,403

DISTRIBUTING VALVE FOR PNEUMATIC HAMMERING TOOLS Filed Dec. 30, 1940 3 Sheets-Sheet 3 ATTORNEY.

Patented Nov. 16, 1943 t ass gns DISTRIBUTING VALVE FOR PNEUMATIC HAMMERING TOOLS Fi'ithiof P. Forss, Aurora, Ill., assignor to Indef pendent Pneumatic Tool 00., Chicago, 111., a

corporation of Delaware Appucaisnnecemba so, 1940, Serial No. 372,227

This invention relates to improvements in distributing valves for portable pneumatic hammers and like tools.

The distributing valves heretofore employed in seats.

sary.

and laterally.

the cylindrical valve member enables simple passages to be provided in the block for the direct flow of air pressure therethrough. to the tool cylinder. ,In addition, the cylindric valve member these tools have been of various typesJThe sleeve contributes to inexpensive and less complicated and the spool types which depend upon a sliding machining for the valve member and the bore action for controlling the supply of pressure fluid in the block to mountand retain it. to the opposite ends ofthe tool cylinder are sub- As to the bore, I make it laterally larger than ject to friction and wear. This results in leakage the diameter of the valve member. so that the and lowers the efliciency of the tool. Small parvl0 valve member may shift automatically to change ticles of scale, rust or dirt carried into the valve the how of live air pressure to theopposite ends by the compressed air are likely to interfere with of the tool cylinder in'the operation of the tool the valve action even to the extent of preventing and in addition provide the bore at points above its operation. Even ordinary lubricating oil conand 'below t e valvemember with substantially gealing, due to the lowering of the temperature flat and tangential seats to. S ppo thelvalve caused by the expansion'of the compressed air, member Within the bore for both lateraland frequently interferes with the free action of these revoluble shifting. sliding valves because of the sticking produced by A further object of my invention is .to provide the lodgement of the oil'on the valve and its the bore at thelports which the valve member Moreover, the repair or upkeep costs on serves with seating Surfaces on arcs of the Sa e these valves are high on account of the elaborate radius as the valve member so that p per sealvalve design and the accurate 'machining necesing can be maintainedbetween the valve member r and the block when the valve member closessaid The plate valve necessitates numerous right ports. t l angle turns in the air channels of the valve block. .25 A further obj ct oi ny inv nti n i t p v This makes the action ofthe tool sensitive to the bore with channels located between these changes'in the air pressure. Moreover, the flat valve seats and the valve supports above and contact surfaces of the plate valve and its seats below the valve member so that'the valve member within the valve block are also sensitive to the "may be supplied through the bore with air preslodgement of dirt and the like between them pre- 3H sure in any shifted position'of the valve member venting perfect sealing against air leakage. within'the bore. I i

The rocking valve of the semi-tubular type 'Aj further object of my invention is to close requires pins or equivalent means to-interengage the opposite ends A of the bore by plugs, which the valve member to center and holdit'in its plugs retain the valve member in its operative supporting block. Tool vibration from the rapidposition within the bore and which plugs incerly hammering strokes of thepiston is likely to jar tain types of tool designs to'be hereinafter rethese pins loose and, the disintegration which ferred to, may be employed as keying means for results causes the pins to break. 7 centering the valve block with respect to the In accordance with my invention, I overcome registerable air flow passages in the tool Cy the objections referred to by providing acylindric 0 A further object of my invention is to provalve member and mount it in its supporting vide a ring-like type of mounting for the valve block for freedom of movement both revolubly block so that thevalve action of my invention In this way the valve memberin maybe adapted to tools which employ a barrel response to the action of the air pressure thereon diameter larger than the valve block per so. may shift laterally to alternately open and close In connection with the last mentionedadaptathe ports which the valve member controls and tion, my invention has for'its purpose to provide at the same time turn freely'about its axis to I this ring mounting with achannel arrangement reduce wear on the valve member bypresenting which will enable the ports or passages in the different portions of its cylindrical surface to valve block to be connected with the ports or the valve seats in the block'at said ports and ,50 passagesin thetool cylinder in any rotative posithe supports in the block for the valve member tion of the valve'mounting within-the same. and maintain such surfaces and supports free of The invention consists further in the features dirt, rust, scale and congealed oil, if any, by the hereinafter described and claimed; r wiping action which the valve member performs In the accompanyingdrawingsin its revoluble or turning movement. Moreover, Fig. 1 is a longitudinal sectional view with parts in elevation of a portable pneumatic hammer equipped with a distributing valve assembly of my invention, the cylindric valv member being shown in its shifted position for supplying air pressure to the rear end of the tool cylinder;

Fig. 2 is a similar view with the handle member broken away and showing the valve member in its shifted position for furnishing air pressure to the front end of the toolcylinder;

Fig. 3 is a vertical sectional view taken on line 33 of Fig. 2;

Fig. 4 is a horizontal sectional view taken on line 44 of Fig. 2;

Fig. 5 is a top plan view of the removed from the tool;

Fig. 6 is a bottom plan view of said valve assembly;

Fig. 7 is a cross-sectional view taken through the valve assembly on line 1-1 of Fig. 5;-

Fig. 8 is a perspective view of the cylindric valve member;

Fig. =9 is a sectional view similar to that of Fig. '1, but showing the form of the valve assem- Fig. 13 is a view looking into the rear end of the barrel to show the dowel pin and the longitudinal passages in the barrel for certain of the ports inthe valve'block.

In the drawings, I have shown my invention applied to two specifically different types of portable pneumatically operated hammering tools. -In Figs. 1 to 8 inclusive, the inventionis shown applied to a chipping hammer or similar tool, while in Figs. 9 to 11 inclusive, the invention is shown applied to a clay digger or other larger type of pneumatically operated percussive tool. In both embodiments, the fundamental feature of the invention is the same, namely, .a valve action which employs afreelyrevoluble and laterally shiftable cylindric valve member to control the distribution of compressed air to the opposite ends of the tool cylinder for reciprocating the hammering piston therein. 7 i

Referring first to Figs. 1 to 8 inclusive: 1 indicates the barrel of the tool I and 2 indicates the cylinder which the barrel provides for the reciprocating hammering piston -3. A chisel 4 extends into .the cylinder 2 at the front end of the barrel to receive the blows of the piston 3. A bushing 5 is fitted within the front end of the barrel to support the chisel shank as shown.

A handle member 6 is secured to the rear end of the barrel by means of its tubular extension I which fits over the barrel and has a screw threaded connection therewith as shown in Figs.

,1 and 2. The extension I is preferably integral with the handle member and the latter when screwed down on the barrel closes the rear end thereof. The handle member contains a recess or cavity 8 over the rear end of the barrel to furnish the pressure fluid, such as compressed air, to the valve block 9 to be presently described. A live air passage ill in the handle member '6 connects with the cavity 8 and a nipple fitting ll valve assembly at the rear end of the handle for the air supply hose (not shown) The flow of live air through the passage III to the valve block 9 is controlled by a throttle valve (not shown), its operable lever I2 being accessible from the outerside of the handle member as in tools of this character.

The distributing valve assembly of my invention is located at the rear end of the cylinder 2 within a recess I 3 provided in the barrel I as shown in Figs. 1 and 2. This valve assembly includes the valve block 9 heretofore referred to, and

' said block is clamped in the recess against a seat M at the bottom thereof by the handl member '6 when -screwed down on the barrel. The block .9 and the recess, 13 are circular, the block conforming to the recess and having peripherial contact with the cylindric wall thereof as shown in Fig. 4. The contacting surfaces between the parts have a ground fit to avoid air leakage.

The block .9 closes the rear. end of the cylinder 2 and :is held from rotative movement therein by a keying arrangement, two formsof which are shown, one inFigs. 1 to 7, inclusive and the other in Figs. 12 and 13. The block 9 has an axial dimension tozextend slightly above the surrounding wall of the barrel I so that the handle memher 6 may engage the block to clamp it in the recess l3. For this purpose, the handle member has an annular shoulder l5 about cavity 8 and the block 9 has an upwardly extending marginal portion 46 to provide a seat for said shoulder. These parts also have a ground fit. With this arrangement as described, the central portion of the uppersurface of the block 9 is left free for direct exposure to the air feed cavity 8.

The block 9 is preferably made of solid metal, such as steel. and is provided with a diametrically disposed bore 11- extending completely through the block from oneside to the other, as shown in Figs. 3 to 6 inclusive; The bore I1 has its end portions made somewhat larger in diameter than its mid-portion l 8 and circular to provide recesses Ila, 11b to mount closing plugs 19, 20. The recesses Ila, .l-lb are alike in diameter and provide annular shoulders l'lc, l'ld at their inner ends constituting seats for the respective plugs 19,20. The latter are alike in shape and dimenouter .side :surface'of the block as shown in Figs.

3 and 4. The recess I3 is provided with an axially extending groove or channel 2! in its side .wall at one point in its circumference to receive the projecting end of the plug 20.. This holds the block 9 from rotation in the recess l3, and centers the block in respect to the air supply passages in the barrel I next to be described. The channel 2| extends through the upper edge of the recess l3 to provide for the insertion of the block 9 into and its removal from said recess.

The mid-portion l8 of the bore I! accommodates a cylindric valve member 22. This valve member is substantially equal in length to the axial dimension of the mid-portion ll? of the bore and is retained therein by the end plugs [9, 28

as detailed in Figs. 3 and 4. The plugs extend radially inward from the seats llc, lld to provide abutting surfaces for the opposed end walls of the valve member. The plugs I9, 20 are held The bore section I9 is milled to'provide sub-- stantially flat upper and lower supporting surfaces 23, 24 for thevalve member 22 and' these supports not only extend the full length of the bore I8, but are spaced apart only slightly greater than the outside diameter of the valve member. These supportsnare substantially tangential 'to the outer cylindrical surface of the valve member and provide for its free movement within the bore.- This movement is not only rotative about the axis of the valve member; but is lateral due to the enlarging of the bore onopposite sides of the supports 23, 24 beyond the diameter of the valve member (see Figs. 1, 2 and 7).

The enlargements just referred to comprise the side portions of the bore and have curved surfaces 25, 26 on arcs of the same radius as'the outside diameter of the valve member. Hence, the valve member 22 when in contact with either of these seats closes theportsZl', 2B which open through them; It 'is tobe observed from Fig. 7 in particular, that the curved seats 25, '26 are diametrically disposed and are alternately engaged by thevalve member in its lateral shifting back and forth within the bore.

The ports 21, 28 are at the ends of passages 29, 29a drilled into the block 9, from one side thereof and across the bore l8. These bori s terminate within the block and have their inner ends closed by the metal of the block." The outer ends of the borings are closed by the side wall of the recess l3 when'the block is inserted therein. As shown in Figs. 4 and 6, the passages 29, 29a are in alinement on opposite sides of the bore l8 and are suflicient in'number to furnish live air to the valve member 22 along the greater portion of its length. In practice, the passages are parallel and open one into the other along their sides to furnish a relatively large volume of air to the valve member 22.

The bore IB is further enlarged by the provision of a number of channels 39 to 33 inclusive formed in the block between the supports 23; 24 and the valve seats 25, 23, respectively, as detailed in Fig. 7. These channels enable the-block to furnishlive air pressure to the bore IS in any shifted position of the valve member. The channels to 33 also localize the areas of the seats 25, 26 to a relatively small portion ofthe outer circumference of the valve member so that the greater portion of the valve member is left free for exposure to the air pressure within the tool." It will be noted from Figs. 4 and 7 that the bore l8 between the valve seats 25, 26 is only slightly wider than the diameter of the valve member 22. Hence, the valve member is required to make only an extremely small lateral stroke to open and close the ports 21, 28. The distance the valve member travels is only'a small fraction of the radius of the valve member; This results in a very quick acting tool. short lateral stroke of the valve member isthe fact that the channels 39 to-33are large, extend longitudinally for the full length of the bore l8 and are in pairs above and below the valve member on opposite sides of thevalve axis. This Coupled with this very providesfor a large flow of live air to the bore 18 the insta'nt'the valve member shifts to open a port-and results in instantaneous starting of the tool to deliver blows as soon as the throttle valve is opened, whether fully or partially. This makes the tool quick and certain in action and easy to control enabling the operator when desired to deliver light blows for light work and heavy blows for heavy work at full power proportionate to the :amount of live air admitted tothe tool at the throttle valve. The'channels are large in that they occupy the greater portion of the circumference of the bore b'etween the valve supports 23, 24 and the valve seats 25, 2'6 with the longitudinaledge'sof the channels relatively close to the supports and the'valve ports, respectively.

tersects the passage 29a. The passage 34 opens through the lower side. of theblock through a cavity 36 which registers with the rear end of the piston" cylinder 2. The other passage 35 opens through the lower surface of the block beyond the cavity 36 in that portion of the block which engages the barrel I at the seat M. The tool barrel I has one or more longitudinal passages 31 which=register with, the passage 35 when the parts areassembled. ,The passages 34, 35 are made to have substantiallythe same size as the passages 29, 29a which they respectively intersect so that a full volume of air is supplied to the tool cylinder. The passages 34, 35 are drilled in the same manner as the passages 29, 29a- This is indicated in Figs. land 6.

1 The air intake openings for the block 3 are -marked 38, 39. These'openings are drilled into the block from its upper side and connect the cavity; 8 withthe bore It on opposite sides of the upper valve support23. The ports 38, 39 open into the respective channels 30, 3| and hence live air is suppliedto the. valve member 22 in either of. its shifted positions. The ports 38, 39 comprise the size and number desired for controlling the speedof reciprocation of the hammering piston 2. I might remark at this point that by varying the number and size of these ports, the volu'meof pressurefluid admitted to the bore I8 maybe controlled. Hence,-for a small size ham mer, the. inlet ports would be small in size, while .forthe larger size hammer the inlet ports would be'larger without changing the size of the valve :.block.- This is a decided advantage in tool design in thata' valve block of one size may serve different sizes of hammers.

The key arrangement described holds the valve block 9 inposition with its passage 35 in register with the barrel passage 31. This passage leadsto the front end of the cylinder 2 and there connects with said cylinder .bya port 40. The barrel is provided with another passage 4!. The

upper end of this passage is closed by the lower wall of the valve block when the parts are assembled and is connected into the-cylinder 2 by two longitudinally spaced ports 42,43. Both of these ports are controlled by the piston 3 in its reciprocating'move'ment. The upper port' 42 is "located approximately -mid-Way between the ends of the passage 4|; while the lower port 43 exhaust passage for the tool andw-isconnected to the atmosphere -by a port 44 and ail-annular channel 45 on the outer side of the barrel Ibehind anexhaust deflector clip 46 as well understood in this art.

The valve assembly shown and described operates-as follows: When the parts'are positioned as in :Figs. 1 andfi', the valve member 22 has been shifted laterally into closing position'in respect to the .port 26 in the. valve block 9. The other port 21 is now open to the live air pressure supplied; to the toolthrough the handle 6. This air pressure enters the rear endof the cylinder 2 through the block passage -34 and thehammer pistonrZ is driven forwardly on its .power stroke. The front endof the cylinder is at this time connected to the exhaust passage 41. through the port '43. As soon as the piston 3 uncovers the upperv port '42 the rear end of the cylinder 2 is how connected with the exhaust passage 4!. The forward port 43 is now closed by the piston as shown in Fig. '2. This cuts off the forward end'ofsthe cylinder to the exhaust with theresult that the air entrapped in the cylinder between the tool shank/4 and the forward end of the piston is compressed in the continued forward movement of the piston; This -com pressed air is forced into the passage 31 towards the valve block 9 through the ,port '40. Duezto the fact that the side of the valve member 22 facing the port 21 is now under a reduced pressure because of the rear end 'of the cylinder being open to the atmosphere through the exhaust, the force of the air compressed by the piston on its forward stroke will operate through the passage 35' and the port 28 to shift the valve member 22 laterally towards the right 'a's shown in Fig. 2. This is aided by the live air pressure which is on the 'surfaceof the valve member facing the port 28 and the valve member is shifted across the boretoclose the port 21. The port 28' is now open and live air pressure will be admitted to the front end of the cylinder through the passage '31 and its port 411 to-drive the piston rearwardly on its returnstroke.

port 43, the rear port 42 is closed and the rear end of the cylinder is cut-off from the exhaust,

while the forward end of the cylinder is conadmitted to the rear end of the cylinder 2 to drive the piston forwardly. .These operations repeat in the alternate shifting of the valve member 22 by the action of the air pressure thereon. The volume of air admitted to the bore I8 through the-inlet. ports 38, 39 is controlled by the combined area of said ports.

In connection with the foregoing, it will be observed from Figs. 1, 2, 5 and 7 that the ports 33 are larger and greater in number than the ports 39.. The purpose of this is to supply a greater volume of air to the tool cylinder on the p'ower'stroke of the piston than on .its return stroke. The point is that the ports for .the. power stroke have a greater combined area than the portsfor the return stroke; This may beaccomplished within the drilling limitations in the relatively tough-steel used for the valve block by making the ports for the power stroke side slightly larger and greater in number than the ports for the return stroke. Asdepicted in Fig. 5, the ports 38, 39 are distributed along-the length of the bore l8 so as to furnish-live air all along the valve member 22.

bore l8 transversely of its longitudinal axis. In

this way, the ports 38, 39 constitute the sole inlet means for the bore and the entire valve assembly may be fitted within the barrel at the rear end of the cylinder, and in axial alinement therewith to be clamped in place by the handle and be housed within and protected by the barrel.

Referring now to Figs. 9 to 11 inclusive;

In this embodiment the'valve action as pre- .viously described is the same, but the construction makes possible the adaptation of this valve action to the larger types of hammering tools, for example clay spades or clay diggers. In tools of this character, the barrel marked 41 in Fig. 9 is considerably larger in diameter than the barrel l of the chipping hammer shown in the previous figures. This larger barrel increases the diameter of the recess (marked 48) at the inner end of the barrel to seat the distributing valve assembly. Because of this, the valve assembly is constructed of two interfitting parts as followsz The outer part 49 which seats in the recess 48 is in the form of an annulus or ring and serves as a mounting for the inner part 50 which constitutes the valve block. The valve block 59 has a radial extension 51 at its upper-end to overhang the ring 49 and support the block within the ring as shown in Fig. 9. The handle member 53 of the tool is secured to the rear endoi the barrel 4'! by side bolts or other desired means a-nd zseats against the fian'geil on the valve block 5!) to hold the latter and the supporting ring 49 in place in the tool. -t

The handle member 53 is providedwith an air supply cavity 54 over the block 50 and-this cavity connects with an air supply passage 55 within the handle unit. This in effect is similar to the construction shown-in Fig. I. It is to'be understood that the handle member 53 is provided with a manually operable throttle valve and-has means whereby the air supplyhose may be connected to the supply passage 55'as in tools of thischaracter.

The valve block 50 is provided with a bore having a section l-8a of the same design as the bore in the valve block 9. This bore mounts a cylindric valve member 22a similar to the corresponding valve member in the block 9., The action of the valve member 220, is exactly the same as the action of the valve member-22 and where the structural parts are alike corresponding reference characters are-employed. The differences between the two forms, .in addition to those already pointed out, are as follows:

The plugs 56,- 51 which close the opposite ends of the bore ISa'and their recesses 58, 59::are

uniform in axial dimension. This enables the outer ends of the plugs 56, 51 to be fiush with V This arrangement locates the ports 38, 39 within the circum-- no need for making a'groove in'the its circumference with an annular groove .BI in the bottom surface of the mounting 49 by passages 62, 82.. The groove Blfaces the bottom of the recess 48 in which the ring. member 49 seats and connects with the several longitudinal passages 63 provided in the barrel 4'! asdetailed in Fig. 9. The passages 63 are suflicient in number to furnish the desired volume of air.to the tool cylinder 52 for reciprocating the hammering piston 65 therein. The passages 63 are connected by a port 66 with the forward end ofthe cylinder 52 beneath the piston element 65 while one or more passages (i l, also in'the cylinder 52, are connected by a port 61 with theintermediate part of the cylinder. The port 61 connects with the atmosphere behind anexhaust deflector-clip as in tools of this design. Also, as in tools of this character, the passage or passages 64 when drilled through the inner end of the cylinis clamped in place by handle member Ba screwed on the barrelas shownin Fig. 12.

The dowel pin -'H is anchored in the barrel la and enters a bore 13 provided in the valve block to receive the pin. Thevalve member 22b is similar to the valve 22 previously shownand described.

The valve block 12 is provided on its underside with an annular channel 14 and this channel serves all of the longitudinal passages 15, 15 located inthe barrel la for supplying the desired airvolume to the forward end of the barrel cylinder 2a.

In all of the forms, as before stated, the valve action is the same. The advantages of a freely revoluble and laterally shifting cylindrical valve member are as follows: No pins or equivalent means .to break or jar loose are required when thevalve member inwplace or hinder its. free lateral and rotative movement. Friction and wear are practically eliminated because of the valve member being cylindrical and free torevolve presents different portions of its cylindrical surface to the valve supports 23, 24 and to the valve seats 25, 26. This distributes thewear on the valve member all around its circumferential surface and in addition makes the entire outer der 52 are closed by a plug 64a in Fig. 9, to close 7 p the inner end of the passage to the-air supply channel EH.

Thevalve block is provided with two sets of passages on opposite sidesof the valve member 22a in somewhat the same manner as shown in Figs. 1 to 7 inclusive. The passage 69 which connects the bore I8a with the inner end of the cylinder 52 opens through the bottom surface of the block 56 over said cylinderr The passage 76 connects the opposite side of the bore [8a with the annular channel 60, said channelopening on the inside of the ring=mounting 49 as shown. In this arrangement, it is apparent that the passage ii! in the valve block is connected with the channel 60 in any rotative position of the valveblock Within. its mounting 49, and as before stated, the annular groove BI connects the passages ill with the barrel passages 63in any rotative position of the ring 49 in the recess With this arrangement, no keying connection is required and hence production time and machining costs are reduced'because there is 'barrel'for either of the plugs .56, 51. The advantage of the disclosure in Figs; 9- and 10 is that thevalve action of my invention is adaptable to the larger and more powerful tools in that the mounting 49 makes possible the insertion of the valve action in tools havinga barrel diameter greater than the valve block per se.

In Fig. 12 I have shown a form of my'invention in which a dowel pin 'H isemployed for centering the valve block 12 and holding" it against rotative movement. within thetool assembly. The construction illustrated is similar to that shown in Figs. 1 to 8 with the exception that the plugs which close the opposite ends of the bore 1% are terminated flush with the outer cylindrical surface of the valve block H as shown in Figs. 9 and 10. Otherwise, the valve action for the construction is the same as shown in Figs. 1 to 8. The valve block" seats within a recess I3a at the inner end of the barrel la and surface of the valve member a valve surface. Moreover, with the valve member freely revoluble the travel of the valve member about its axis keeps thevalve seats. and the supports clean and free of dust, dirt, rust and congealed oil, if any,

by a wiping action and the proper sealing canybe maintained which is so essentialtoefiective tool operation. Added to this is the fact that cylindrical form of the valve member renders it effective in any position in which the tool'may be 'few parts which keeps theupkeep and repair down. The. cylindric valve member also contribdurability of the parts.

. utes to a simple porting and passage arrangement in the block'for the direct flow of air therethrough and lower costs in production and machining. The valve member is preferably made of a steel relatively harder than that of the block to'provide for ease in the valve action and All contacting surfaces are. ground to avoid air leakage. 1 V The details of construction'and arrangement of parts shown and. described may be variously changed and modified without departing from the spirit and scope of my inventiom'except as pointed out in the'annexe'd claims.

I claim as myv invention 1. In a pneumatic hammering-tool, a barrel to. the opposite ends of the cylinder, a cylindrical distributing valve member located within the bore and operable by the fluid pressure supplied to the cylinder through the bore, said valve member being slidably and rotatably supported with the bore by said valve supports for movement into and out of contact with the valve seats to alternately open and close the ports'to reciprocate the piston within the cylinder, plug elements closing the oppositeends of the bore andheld therein by contact with the adjacent surrounding-wall of: the barrel, at least one of 'said plug elements having a; keying connection with the barrel for centering and: holding the valve block from rotation therein, an exhaustfor thecylinder, and inlet ports in the valve block connected to the bore forsupplying pressure fl uid thereto. V I

'2. In a pneumatic hammering tool; a barrel contain-ing a cylinder; a hammering: piston therem, a valve block: located in said barrel at one-end of the cylinder and having a bore extending therethrough in crossing relation to the: cylinder, said bore having opposed valve seats and valve supports therebetween intermediate theends- Of the bore, ports. connectingthe bore at the valve seatstOzthG'OPDOSitGBIldS of: the-cylinder,- plug elements closing theopposite ends of the bore connected to the borefor supplying pressure fluid.

thereto r 3. In a portable: pneumatic hammeringtool', a cylinder, a piston therein, avalve block at one end of the cylinderandihaving a bore having=op* posed valve seats and valve: supports therebetween, ports-.connectingthe boreatthe valve-seats tothe opposite ends of the cylinder,:a hollow cylindrical distributing valve member: rotatably and. slidably mounted within: the bore on the valvezsupports, said J bore between: the: valve seats being, only. slightly wider. thanthe diameter ofithe valvermember' for the lateral; sl'nfting: thereon by the pressure fluid zsupplied'totthe cylinder through thebore, thelateraltravelof the valve member being. only a small fractionof the radiusiofi the valvemember. to alternately open. and; close; said ports rapidly toi reciprocate-the piston: withimthe cylinder, said valve, supports being tangential; to the valvemember-and:fihevalveseats being on-the same radius-e the valve member, said block+ being provided-independently of the valve member with channels opening into the; borebetween the valve supports and the valveseatsfor supplyi pressure fluid to the borein-any; shifted;- position of the valve member, said. channels extending longitudinally. of the bore inpairsabove and-. be low. the valve .member. on. opposite. sidesmf. the valve axis and occupying the greater portion; of the circumferenceofthe bore between the, valve supports and the valve seats with the longitudinal edges of J the channels. relatively. close ;to ,the sup ports andthe ports,'.resp.ectively, to provide large cl'lajlrmels, ,whereby, a small shifting motion of the valve. member. to.v open, a port.) results in, a. large eczema transversely ofthe valve axis.

In1.a=.p rtab1epneumatic hammering. tool, a

barrel providing a cylinder, a piston reciprocable' therein on its power. and. return strokes, a valve block; clampedin the barrel atone endof thecylindex: and. having ,.-.bore:extending cross-Wise of the cylinder and provided with opposed. valve seats-and'valve supportstherebetween, ports con-- necting thebore atrthevalve-seats to the opposite endszof thecylinder, a-rhollow cylindricaldistrihutingvalvexmember. rotatably'andslidably mountedwwithin the. bore. on. the valve supports, said bore between. the valve seats being only slightly wider thanthe diameter of. thevalve member'for the lateraLshifting thereofby the pressure fluid supplied-to;the:.cylinder through the bore,.the lateral-shifting of the=valve member being only a small: fraction of the radius of the valve member to; alternately open. and closev said. ports rapidly to reciprocate-:the piston withintthe cylinder, said valvesupports beingtangential tothe valve member. and the valve seats being 0111 the same radius as the valvemember, said block being. provided independently of the Valve member with; channels openinginto the'bore between the valve supports;v and: the valve seats for supplying; pressure fiuidto: the bore: in. any shifted position: of the valve-member;.saidchannels extending longitudinallyof theubore for.- substantially. the fuILIength' ofthevalve member and; disposed in pairs above and; below: the .valve member on opposite sides of the valve axis, said channels occupyingthe greater. portion; of. thexcircumference of; the bore between the:valve:supports. and the valve-seatswith the? longitudinal edges; of; the channels relatively 'closetorthesupportsand the seats, respectively,

to providerlargechannels, whereby asmalli-shiftinggof. thetvalvemembento open a port .results in aslargeflow'of pressurefluidifrom apair. ofrchan nels -.toathe;adjacent:p'ort.,for instantaneous; starting: of the tool, said-ports being elongated andextending, lon itudinally-of: the bore for-the greater portion: of:v its: length: asnoccupied; by the valve member to convey the: largezflow; of. pressure1fluid to vthe: cylinder,,. an: exhaust for: the cylinder; and inlet ports in the blockconnectedrtoone of.:.the channels; of each: pair intermediate the ends thereoffor. supplying: pressure; fluid to. the, bore transversely: of: the. valve. axis, said. inlet. ports beingiarrangedainr groups if or: the: respectivechannels. with .the.=individual ports --.of. one group smallen thamthemorts of. the: other groupxand; having the-combined area .of; the inlet:p0rtsfor the power stroke of the piston greater than; the combined area. of the .inlet;.portsfor the return-stroke of the piston. g

V. r FRITHIOF P; FORSS. 

